The Whimsical Penguins Introduction
Anil Ali
Adil
Dhvel Patel*
Harishangaran Krishnamoorthy
Michael Almeida
INTRODUCTION
The choice of studying polymorphism in snails over humans is because they are easily available i.e localised populations compared to humans where a lot of travelling would be done to obtain samples, proving to be a time consuming and expensive choice. Such a study focusing on humans also proves to be difficult due to immense gene flow as we live in a relatively footloose global village.
Cepaea is a cross fertilising hermaphrodite (possesion of both male and female gonads). The genus consists of two populations; C.nemoralis L and C.hortensis Mull. Our study is primarily based upon the C.nemoralis population. This a western European species which prefers warmer microclimates. C.nemoralis is known for the polymorphism it depicts for body colour (yellow, brown and pink), for the presence of bands (appearance and number) as well as the colour of the lips on the shell. It is understood that there is a supergene (group of neighbouring genes close enough on a chromosome to be genetically linked) consisting of polymorphic alleles for shell colour, presence or absence of bands, lip colour and type of band pigmentation. Moreover, populations of C.nemoralis which are a few hundred metres apart can have fixed alleles at a particular locus.
The two habitats focused upon were; the grassland and the hedgerow. Initially it was planned to collect thirty snails from each of the habitat within a 5m radius.The distance between two subsequent populations i.e. habitats was fixed 25m in order to nullify the effects of gene flow between populations. However, in practical, it was found that there were hedgerows in between grass lands which we had to avoid and that a 15m radius was used to collect snail shells..
The isolation of d>25m used to reduce gene flow will not erradicate outliers corresponding to snails that have been carried by predator; song Thrush (Turdus ericetorum) or by sudden gust of wind etc. Six samples were obtained; three from each habitat thereby ensuring replication of sampling thrice. The count was performed by one allocated member of the group to maintain consistency.
As the whole of the snail population was not being sampled, any finding significant or otherwise was subjected to the chai square test. Initially, the data from within the same type of habitat was used and any discrepancy accounted for. In the absence of significance, the data from both the habitats were observed. The chai square test informed us of whether or not the null hypothesis was true for the corresponding p value.
Null hypothesis: Polymorphism in C.nemoralis can be explained using the evolutionary mechanisms selection and genetic drift.
The null hypothesis would be supported with the observation of significant amount of a particular type of snails within one habitat. It may be due to selection by predator or microclimatic factors.
However, the occurence of a randomised types of snails would counter the argument and rule out selection. This could be due to snails being carried by birds or wind, previous study groups throwing snails around etc.
Anil Ali
Adil
Dhvel Patel*
Harishangaran Krishnamoorthy
Michael Almeida
INTRODUCTION
The choice of studying polymorphism in snails over humans is because they are easily available i.e localised populations compared to humans where a lot of travelling would be done to obtain samples, proving to be a time consuming and expensive choice. Such a study focusing on humans also proves to be difficult due to immense gene flow as we live in a relatively footloose global village.
Cepaea is a cross fertilising hermaphrodite (possesion of both male and female gonads). The genus consists of two populations; C.nemoralis L and C.hortensis Mull. Our study is primarily based upon the C.nemoralis population. This a western European species which prefers warmer microclimates. C.nemoralis is known for the polymorphism it depicts for body colour (yellow, brown and pink), for the presence of bands (appearance and number) as well as the colour of the lips on the shell. It is understood that there is a supergene (group of neighbouring genes close enough on a chromosome to be genetically linked) consisting of polymorphic alleles for shell colour, presence or absence of bands, lip colour and type of band pigmentation. Moreover, populations of C.nemoralis which are a few hundred metres apart can have fixed alleles at a particular locus.
The two habitats focused upon were; the grassland and the hedgerow. Initially it was planned to collect thirty snails from each of the habitat within a 5m radius.The distance between two subsequent populations i.e. habitats was fixed 25m in order to nullify the effects of gene flow between populations. However, in practical, it was found that there were hedgerows in between grass lands which we had to avoid and that a 15m radius was used to collect snail shells..
The isolation of d>25m used to reduce gene flow will not erradicate outliers corresponding to snails that have been carried by predator; song Thrush (Turdus ericetorum) or by sudden gust of wind etc. Six samples were obtained; three from each habitat thereby ensuring replication of sampling thrice. The count was performed by one allocated member of the group to maintain consistency.
As the whole of the snail population was not being sampled, any finding significant or otherwise was subjected to the chai square test. Initially, the data from within the same type of habitat was used and any discrepancy accounted for. In the absence of significance, the data from both the habitats were observed. The chai square test informed us of whether or not the null hypothesis was true for the corresponding p value.
Null hypothesis: Polymorphism in C.nemoralis can be explained using the evolutionary mechanisms selection and genetic drift.
The null hypothesis would be supported with the observation of significant amount of a particular type of snails within one habitat. It may be due to selection by predator or microclimatic factors.
However, the occurence of a randomised types of snails would counter the argument and rule out selection. This could be due to snails being carried by birds or wind, previous study groups throwing snails around etc.